LXR linux/arch/arm/include/asm/percpu.h

   1/*
   2 * Copyright 2012 Calxeda, Inc.
   3 *
   4 * This program is free software; you can redistribute it and/or modify it
   5 * under the terms and conditions of the GNU General Public License,
   6 * version 2, as published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope it will be useful, but WITHOUT
   9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11 * more details.
  12 *
  13 * You should have received a copy of the GNU General Public License along with
  14 * this program.  If not, see <http://www.gnu.org/licenses/>.
  15 */
  16#ifndef _ASM_ARM_PERCPU_H_
  17#define _ASM_ARM_PERCPU_H_
  18
  19/*
  20 * Same as asm-generic/percpu.h, except that we store the per cpu offset
  21 * in the TPIDRPRW. TPIDRPRW only exists on V6K and V7
  22 */
  23#if defined(CONFIG_SMP) && !defined(CONFIG_CPU_V6)
  24static inline void set_my_cpu_offset(unsigned long off)
  25{
  26        /* Set TPIDRPRW */
  27        asm volatile("mcr p15, 0, %0, c13, c0, 4" : : "r" (off) : "memory");
  28}
  29
  30static inline unsigned long __my_cpu_offset(void)
  31{
  32        unsigned long off;
  33
  34        /*
  35         * Read TPIDRPRW.
  36         * We want to allow caching the value, so avoid using volatile and
  37         * instead use a fake stack read to hazard against barrier().
  38         */
  39        asm("mrc p15, 0, %0, c13, c0, 4" : "=r" (off)
  40                : "Q" (*(const unsigned long *)current_stack_pointer));
  41
  42        return off;
  43}
  44#define __my_cpu_offset __my_cpu_offset()
  45#else
  46#define set_my_cpu_offset(x)    do {} while(0)
  47
  48#endif /* CONFIG_SMP */
  49
  50#include <asm-generic/percpu.h>
  51
  52#endif /* _ASM_ARM_PERCPU_H_ */
  53